A6A595 Ver la hoja de datos (PDF) - Allegro MicroSystems

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Fabricante

A6A595

8-Bit Serial Input, DMOS Power Driver

Allegro MicroSystems 

6A595

8-BIT SERIAL-INPUT,

DMOS POWER DRIVER

TEST CIRCUIT

INPUT

IO

VO

tav

IAS = 600 mA

DUT

V(BR)DSX

+15 V

Single-pulse avalanche energy test circuit

and waveforms

EAS = IAS x V(BR)DSX x tAV/2

OUT

VO(ON)

Dwg. EP-066-2

CHOPPING-MODE OPERATION

NORMAL LAMP IN-RUSH CURRENT

NOT TO SCALE

CURRENT LIMIT

(CHOPPING MODE)

ON ~ 40 µs

OFF ~ 2.5 ms

IO(chop)

TIME

Dwg. WP-008-1

High incandescent lamp turn-on currents (commonly

called in-rush currents) can contribute to poor lamp

reliability and destroy semiconductor lamp drivers.

Warming resistors protect both driver and lamp but use

significant power when the lamp is off while current-

limiting resistors waste power when the lamp is on.

Lamps with steady-state current ratings to 350 mA can be

driven by the A6A595 without the need for warming or

current limiting resistors.

As shown (the dashed line), when an incandescent

lamp is initially turned on, the cold filament is at mini-

mum resistance and will normally allow a 10x peak in-

rush current. As the lamp warms up, the filament resis-

tance increases to its rated value and the lamp current is

reduced to its steady-state rating. When switching a lamp

with the A6A595, the internal chopping circuitry limits

the current (the solid line) to IO(chop). The device will stay

in the chopping mode until the lamp resistance increases

and the current requirement is less than IO(chop). A side-

effect of this current-limiting feature is that lamp turn-on

time will increase.

6

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

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